The present invention relates to novel substituted pyridine compounds having estrogenic activity, to processes for their preparation, to combinatorial and solid phase methods for preparing libraries of the compounds, to utilizing libraries of the compounds for drug discovery, to methods of treatment and to pharmaceutical compositions thereof.
The solid phase synthesis. of non-peptidic small organic molecules is a rapidly evolving area of research with applications in the preparation of combinatorial libraries. While the solid phase synthesis of peptides is an established, the solid phase synthesis of non-peptidic small organic molecules is still evolving (Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554). In particular, methods for the solid phase synthesis of heterocyclic ring systems of importance to drug discovery is an active area of research.
Pyridine derivatives are commonly used as pharmaceuticals (Gordeev, M. F., et al. Tetrahedron Lett., 1996, 37, 4643-4646). Trisubstituted pyridines are a useful class of compounds. Karle, et al. (Antimicrob. Agents Chemother. 1989, 33, 1081-1089) describe 2,4,6-trisubstituted pyridines as antiprotozoal agents. Shirai, et al. (WO 96/00213) describe 2,4,6-trisubstituted pyridines as useful for accelerating nerve growth factor production, and also ((WO 96/16942) as useful for ameliorating neuropathy.
Combinatorial chemistry is becoming an important tool for drug discovery and lead optimization (Borman, S. Chemical and Engineering News 1997, 75 (8), 43-62). A combinatorial synthesis requires that at least two components of the product molecules be independently variable, so that all of the combinations of these components can be prepared. A synthesis with three independently variable components is preferable since greater diversity in structure can be produced in the resultant library. Thus, to prepare a combinatorial library of pyridines with a high degree of potential diversity and wide utility for drug discovery using solid phase techniques, it is important to identify a pyridine synthesis in which three components can be independently varied. The solution phase synthesis of pyridines from 1,5-pentanediones and amnonia followed by oxidation is known (Katritzky, A. R. Handbook of Heterocyclic Chemistry, pp. 408-409; Pergamon Press: Oxford, 1985). A variation of this synthesis involves the reaction of a bromomethyl ketone with pyridine, and subsequent reaction of this intermediate with an unsaturated ketone in the presence of ammonium acetate in acetic acid to yield a 2,4,6-trisubstituted pyridine (Krohnke, F. Synthesis 1976, 1-24). The latter synthesis proceeds through a 1,5-diketone intermediate which is not isolated. For a solid phase combinatorial synthesis it is necessary to modify these syntheses to allow for the independent introduction of three variables (the 2,4, and 6 substituents), and to adapt the solution phase synthesis to a solid supported synthesis. The solid phase pyridine synthesis of this invention is achieved by using a hydroxyacetophenone starting material which can be attached to a solid support through the phenolic hydroxy group.
A solid phase synthesis of 2,3,4,5,6-pentasubstituted dihydropyridines and pyridines has been described in Gordeev, M. F., et al. Tetrahedron Lett., 1996, 37, 4643-4646. The compounds are prepared by the Hantzsch pyridine synthesis and therefore all contain acyl or carboxyl groups in the 3- and 5-positions. The solid phase synthesis of the current invention does not yield pyridines with acyl or carboxyl groups in the 3- and 5-position of all products and therefore yields a more diverse set of products.
Multiple compounds can be prepared simultaneously by the solid phase process. The simultaneous solid phase synthesis of a library of 2,4,6-trisubstituted pyridines of the present invention is not known. The preparation of libraries of compounds of the present invention is useful because it provides rapid structural variation and structure-activity information.
The libraries of substituted pyridines synthesized according to the present invention are useful for drug discovery. Screening of the pyridine libraries in an estrogen receptor assay identified compounds with estrogen agonist activity. Estrogen agonists are useful as post-menopausal therapeutics for the prevention and treatment of osteoporosis, atherosclerosis, and Alzheimer""s disease.
The present invention relates to new compounds selected from those of the general Formula (I) and also discloses a solid phase synthesis process for producing new compounds selected from those of Formula (I): 
wherein:
the moiety Z 
xe2x80x83is selected from the group: 
n is an integer of 1 or 2;
R1 is straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, phenyl, or phenyl substituted with fluoro, chloro, bromo, straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, phenyl, alkoxy of 1 to 6 carbon atoms, or methylenedioxy;
R2 is furanyl, pyridyl, thienyl, naphthalenyl, phenyl, or phenyl substituted with fluoro, chloro, bromo, straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, alkoxy of 1 to 6 carbon atoms, or methylenedioxy;
R3 is hydrogen, fluoro, chloro, bromo, nitro, straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, or alkoxy of 1 to 6 carbon atoms;
and all crystalline forms and the pharmaceutically acceptable salts thereof, the enantiomers thereof, the racemic mixtures thereof, and the diastereomeric mixtures thereof.
Among the preferred groups of compounds of this invention are those in the subgroups:
a) compounds having the general formula: 
wherein R1, R2, and R3 are as defined above or a pharmaceutically acceptable salt;
b) compounds having the general formula: 
wherein R1, R2, R3 and n are as defined above or a pharmaceutically acceptable salt.
Among the more preferred compounds of this invention are those of the formula: 
wherein R1, R2, and R3 are as defined above or a pharmaceutically acceptable salt.
The most particularly preferred compounds of Formula (I) of the present invention prepared by the herein described solid phase synthesis processes are:
2-[6-(4-chloro-phenyl)-4-(3,4-difluoro-phenyl)-pyridin-2-yl]-phenol or a pharmaceutically acceptable salt thereof;
2-[4-(3,4-difluoro-phenyl)-6-naphthalen-2-yl-pyridin-2-yl]-phenol or a pharmaceutically acceptable salt thereof;
2-[4-(3,4-difluoro-phenyl)-6-furan-2-yl-pyridin-2-yl]-phenol or a pharmaceutically acceptable salt thereof;
2-(4-benzo[1,3]dioxol-5-yl-6-naphthalen-2-yl-pyridin-2-yl)-phenol or a pharmaceutically acceptable salt thereof;
2-(4-benzo[1,3]dioxol-5-yl-6-thiophen-3-yl-pyridin-2-yl)-phenol or a pharmaceutically acceptable salt thereof;
2-(4-biphenyl-4-yl-6-naphthalen-2-yl-pyridin-2-yl)-4-fluoro-phenol or a pharmaceutically acceptable salt thereof;
2-(4-biphenyl-4-yl-[2,4]bipyridinyl-6-yl)-4-fluoro-phenol or a pharmaceutically acceptable salt thereof;
2-(4-cyclohexyl-6-furan-2-yl-pyridin-2-yl)-4-fluoro-phenol or a pharmaceutically acceptable salt thereof;
3-(4-biphenyl-4-yl-6-naphthalen-2-yl-pyridin-2-yl)-phenol or a pharmaceutically acceptable salt thereof;
3-(4-cyclohexyl-6-furan-2-yl-pyridin-2-yl)-phenol or a pharmaceutically acceptable salt thereof.
The novel process for producing novel compounds of Formula (I) comprises the steps of:
a) attaching a hydroxyacetophenone 1 of the formula 
xe2x80x83or an alkaline metal salt thereof where the moiety Z and R3 are hereinbefore defined, to a solid support to produce an acetophenone 2 
xe2x80x83wherein the moiety Z and R3 are hereinbefore defined, R4 and R5 are independently hydrogen or methoxy, and P is preferably a polystyrene resin support crosslinked with divinylbenzene;
b) reacting said acetophenone 2 with an aldehyde R1CHO wherein R1 is as hereinbefore defined, in the presence of a base to produce an olefin 3 
xe2x80x83wherein the moiety Z, R1, R3, R4, R5, and P are as hereinbefore defined;
c) reacting olefin 3 with a silyl enol ether 4 
xe2x80x83wherein R2 is as hereinbefore defined and TMS is trimethylsilyl, in the presence of a fluoride source such as cesium fluoride to produce 1,5-diketone 5 
xe2x80x83wherein the moiety Z, R1, R2, R3, R4, R5 and P are as hereinbefore defined;
d) reacting 1,5-diketone 5 with ammonium acetate to produce pyridine 6 
xe2x80x83wherein the moiety Z, R1, R2, R3, R4, R5 and P are as hereinbefore defined; and
e) reacting pyridine 6 with a cleaving reagent such as trifluoroacetic acid to produce a compound of Formula (I) 
xe2x80x83wherein the moiety Z, R1, R2 and R3 are as hereinbefore defined.
The present invention also relates to new combinatorial compound libraries selected from those of the general Formula (I) and also discloses a solid phase synthesis process for producing new compound combinatorial libraries selected from those of Formula (I): 
wherein:
the moiety Z 
xe2x80x83is selected from the group: 
n is an integer of 1 or 2;
R1 is straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, phenyl, or phenyl substituted with fluoro, chloro, bromo, straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, phenyl, alkoxy of 1 to 6 carbon atoms, or methylenedioxy;
R2 is furanyl, pyridyl, thienyl, naphthalenyl, phenyl, or phenyl substituted with fluoro, chloro, bromo, straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, alkoxy of 1 to 6 carbon atoms, or methylenedioxy;
R3 is hydrogen, fluoro, chloro, bromo, nitro, straight chain alkyl of 1 to 6 carbon atoms, branched chain alkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, or alkoxy of 1 to 6 carbon atoms;
and all crystalline forms and the pharmaceutically acceptable salts thereof, the enantiomers thereof, the racemic mixtures thereof, and the diastereomeric mixtures thereof.
Among the preferred combinatorial libraries of compounds of this invention are those in the subgroups:
a) combinatorial libraries of compounds having the general formula: 
xe2x80x83wherein R1, R2, and R3 are as defined above or a pharmaceutically acceptable salt;
b) combinatorial libraries of compounds having the general formula: 
xe2x80x83wherein R1, R2, R3 and n are as defined above or a pharmaceutically acceptable salt.
Among the more preferred combinatorial libraries of compounds of this invention are those of the formula: 
wherein R1, R2, and R3 are as defined above or a pharmaceutically acceptable salt.
It is understood that the definition of the compounds of Formula (I), when R1, R2, and R3 contain asymmetric carbons, encompasses all possible stereoisomers and mixtures thereof. In particular, it encompasses racemic modifications and any optical isomers. Optical isomers may be obtained in pure form by standard separation techniques. The pharmaceutically acceptable salts are those derived from such organic and inorganic acids as: lactic, citric, acetic, tartaric, succinic, maleic, malonic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, methanesulfonic, and similarly known acceptable acids. Carboxylic acid salts of the compounds of this invention may be formed with bases such as alkali metals (Na, K, Li) or the alkaline earth metals (Ca or Mg).
The compounds of the present invention may be prepared according to the general process outlined below in Scheme I. 
As shown in Scheme II a resin such as Wang resin 7 (R4 and R5=H, P=polystyrene crosslinked with divinylbenzene) (Wang S.; J. Am. Chem. Soc. 1973, 95, 1328-1333) is converted to a chloro resin 8 with lithium chloride, methanesulfonyl chloride, and a base such as collidine or lutidine in a polar aprotic solvent such as dimethylformamide. 
As outlined in Scheme I, chlororesin 8 is reacted with an alkaline metal salt, preferably the cesium salt, of a hydroxyacetophenone 1 where R3 is hereinbefore defined, to produce an acetophenone 2 where the moiety Z, R3, R4, R5 and P are hereinbefore defined. Acetophenone 2 is reacted with an aldehyde R1CHO where R1 is hereinbefore defined in the presence of a base such as sodium methoxide in a polar aprotic solvent such as trimethyl orthoformate at temperatures ranging from 0xc2x0 C. to 50xc2x0 C. to yield an olefin 3 on a solid support resin where the moiety Z, R1, R3, R4, R5 and P are hereinbefore defined. Olefin 3 is reacted with a silyl enol ether 4 where R2 is hereinbefore defined and TMS is trimethylsilyl in the presence of a fluoride source such as cesium fluoride in a polar aprotic solvent such as dimethyl sulfoxide at temperatures ranging from 25xc2x0 C. to 120xc2x0 C. to yield a 1,5-diketone 5 on a solid support where the moiety Z, R1, R2, R3, R4, R5 and P are hereinbefore defined. A 1,5-diketone 5 is reacted with ammonium acetate in the presence of acetic acid in a polar aprotic solvent such as dimethylformamide at temperatures ranging from 25xc2x0 C. to 120xc2x0 C. to yield a pyridine 6 on a solid support where the moiety Z, R1, R2, R3, R4, R5 and P are hereinbefore defined. A compound of Formula (I) where the moiety Z, R1, R2 and R3 are as defined above is removed from the solid support with an acidic cleavage mixture such as trifluoroacetic acid in dichloromethane.
The present invention accordingly provides a pharmaceutical composition which comprises a compound of this invention in combination or association with a pharmaceutically acceptable carrier. In particular, the present invention provides a pharmaceutical composition which comprises an effective amount of a compound of this invention and a pharmaceutically acceptable carrier.
The compositions are preferably adapted for oral administration. However, they may be adapted for other modes of administration, for example, parenteral administration for patient suffering from heart failure.
It is understood that the dosage, regimen and mode of administration of these compounds will vary according to the malady and the individual being treated and will be subject to the judgement of the medical practitioner involved. It is preferred that the administration of one or more of the compounds herein begin at a low dose and be increased until the desired effects are achieved.
In order to obtain consistency of administration, it is preferred that a composition of the invention is in the form of a unit dose. Suitable unit dose forms include tablets, capsules and powders in sachets or vials. Such unit dose forms may contain from 0.1 to 100 mg of a compound of the invention and preferably from 2 to 50 mg. Still further preferred unit dosage forms contain 5 to 25 mg of a compound of the present invention. The compounds of the present invention can be administered orally at a dose range of about 0.01 to 100 mg/kg or preferably at a dose range of 0.1 to 10 mg/kg. Such compositions may be administered from 1 to 6 times a day, more usually from 1 to 4 times a day.
The compositions of the invention may be formulated with conventional excipients, such as a filler, a disintegrating agent, a binder, a lubricant, a flavoring agent and the like. They are formulated in conventional manner, for example, in a manner similar to that use for known antihypertensive agents, diuretics and beta-blocking agents.
The new compounds of Formula (I) of this invention are useful in treating conditions in mammals characterized by estrogen deficiency such as in post-menopausal women.
In particular, compounds of Formula (I) of this invention are useful as post-menopausal therapeutics for the prevention and treatment of osteoporosis, atherosclerosis, and Alzheimer""s disease in mammals.